A fuel rail assembly distributes fuel to fuel injectors by a fuel rail, and then injects the fuel by the fuel injectors into the air intake passage of an engine. The fuel injectors are controlled by fuel injection command signals issued by the engine's ECU (Electronic Control Unit). During injection by a fuel injector, the amount of fuel in the fuel rail is reduced, and the pressure is reduced, causing a pressure fluctuation inside the fuel rail. Pressure fluctuation causes vibration and noise in the fuel rail and has an impact on the injection effect of the fuel injectors. To achieve a good injection effect, the pressure inside the fuel rail must be kept constant. A damper is an apparatus for maintaining pressure inside a fuel rail. Existing dampers in fuel rail assemblies have the following shortcomings:    (1) they require a larger space for installation;    (2) they have a complex structure;    (3) they have a high cost.